The present invention relates to a semiconductor device and a method of manufacturing the same and more particularly to a technique which is useful for the application to an LCD (Liquid Crystal Display) driver that drives a liquid crystal display unit and manufacturing thereof.
In Japanese patent laid-open No. 11-330247 (patent document 1), a technique is described, which can accurately detect an alignment mark when forming an alignment mark for laser trimming within a chip. Specifically, the surface of a semiconductor substrate made of SOI substrate has a tapered part oblique with respect to the normal direction at least in the peripheral region of the alignment mark and laser light is caused to reflect in a direction different from the normal direction at the tapered part. With the arrangement, it is possible to reduce the reflection of laser light in the normal direction of the semiconductor substrate in the peripheral region of the alignment mark, and therefore, the alignment mark can be accurately distinguished from its peripheral region. Consequently, it is concluded that the detection of an alignment mark can be accurately carried out also when forming an alignment mark within a chip. In this case, the tapered part is formed in the same layer as that of an element isolation region formed over the semiconductor substrate.
In Japanese patent laid-open No. 2000-182914 (patent document 2), a technique is described, which provides a mark with which an image can be stably recognized and detected with high precision in an alignment mark for image recognition to be attached to a semiconductor device. Specifically, in the peripheral region of a cross-shaped mark main body part formed as a solid pattern of aluminum layer, a diffusion reflection layer made of aluminum is formed. As a diffusion reflection layer, a stripe-shaped, grating-shaped, or dot-shaped fine pattern formed by an aluminum layer can be used. Patent document 2 also describes that openings are formed with a fine pattern of stripe shape etc. in an interlayer insulating film in the lower layer and an aluminum layer having an irregular (level differences) pattern corresponding to the pattern of the openings can be used as a diffusion reflection layer. In this case, the diffusion reflection layer formed in the peripheral region of the cross-shaped mark main body part is formed in the same layer as that of the mark main body part.